Since the mid-80's, a type of rotor introduced into the automotive market called a composite rotor has presented maching problems. The composite rotor is made from two materials; the friction disc is made of cast iron, while the hub is made from stamped steel.
The use of two materials lowers the rotor weight by 15 to 20% but also helps reduce noise as well as providing cooler rotor temperatures.
The composite rotor cannot be machined using conventional centering cones and bell clamps. If the standard accessories
are used the rotor will have a chatter in the surface finish that will prevent the rotor from working correctly.
To prevent surface finish problems, the operator should be using a composite rotor kit, Kwik-Way part number 804-8667-75
to attach the rotor to the brake lathe. The kit uses plates to clamp and hold the rotors stamped steel "hat" in order to prevent a vibration.
This vibration is what is responsible for causing chatter within the surface of the cast iron disc.
A dampener used by itself is not effective at preventing this situation, only the use of a composite kit can assure the correct surface finish.
This adapter set can be used with any hubless rotor, and will speed up the actual time required to mount and turn any rotor,
composite or not.